In the past, as a small-sized actuator, an actuator has been known that utilizes a piezoelectric element. An example of this actuator utilizing the piezoelectric element has been described in the following Patent Document 1 or 2.
In Patent Document 1, an actuator has been described that includes an electromechanical conversion element in which an end portion on one side thereof in a length direction is fixed to a pedestal, a driving frictional member connected to an end portion on the other side of the electromechanical conversion element in the length direction, and an engaging member engaging with the driving frictional member. In this actuator, the electromechanical conversion element expands and contracts in the length direction, and hence, the driving frictional member vibrates in a length direction. Owing to a frictional force between the driving frictional member and the engaging member, the frictional force occurring at this time, the engaging member moves in the length direction relative to the driving frictional member. In other words, in the actuator described in Patent Document 1, the expansion and contraction direction of the electromechanical conversion element and a direction in which a driving force occurs are parallel to each other, and the direction of the driving force and the direction of a vibrational displacement are parallel to each other.
On the other hand, in Patent Document 2, an actuator 100 has been described that converts the direction of a driving force illustrated in FIG. 14. The actuator 100 includes a plate-like shaft fixing member 102, a pair of vibrating plates 103a and 103b, a substrate 104, and a shaft 101. One end of the shaft 101 is connected to the shaft fixing member 102. The pair of vibrating plates 103a and 103b supports both end portions of the shaft fixing member 102, and extends in a direction perpendicular to the shaft fixing member 102. In the substrate 104, the end portions of the vibrating plates 103a and 103b, located on the side opposite to the shaft fixing member 102, are fixed. Piezoelectric elements 105a and 105b are fixed to the vibrating plates 103a and 103b. In association with the expansion and contraction deformation of the piezoelectric elements 105a and 105b, the vibrating plates 103a and 103b extending in the direction perpendicular to the shaft fixing member 102 are subjected to flexion deformation. As a result, the directions of driving forces occurring from the piezoelectric elements 105a and 105b are converted, and the shaft fixing member 102 is vibrationally displaced. Owing to this, the shaft 101 vibrates, and the engaging member 106 is driven.
Patent Document 1: Japanese Patent No. 4154851
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2009-254154
In an electromechanical conversion element expanding and contracting in parallel to the direction of a driving force in such a way as described in the above-mentioned Patent Document 1, in order to obtain the sufficient displacement amount of vibration, it is necessary to lengthen the electromechanical conversion element in the direction of the vibration. Therefore, in such an electromechanical conversion element as described in Patent Document 1, there occurs a problem that it is difficult to perform miniaturizing in the direction of a vibrational displacement.
Also in the actuator 100 described in Patent Document 2, which converts the direction of the driving force, in order to obtain a large displacement amount, a method is adopted where the vibrating plates 103a and 103b are lengthened in parallel to the direction of the vibrational displacement so as to increase a flexion deformation amount. Therefore, in the actuator 100 described in Patent Document 2, there occurs a problem that it is difficult to perform miniaturizing in the direction of the vibrational displacement where the directions of the driving forces occurring from the piezoelectric elements 105a and 105b are converted.